Dinarmus

Thomson, 1878

Dinarmus is a of chalcidoid wasps in the Pteromalidae with nearly distribution. in this genus are larval-pupal ectoparasitoids of bruchid beetles (Chrysomelidae: Bruchinae), particularly pests of stored legume seeds such as cowpea. The genus includes economically important agents, notably D. basalis and D. vagabundus, which are deployed in programs targeting Callosobruchus species. Research on D. basalis has revealed complex discrimination , facultative , and olfactory host location mechanisms.

Pronunciation

How to pronounce Dinarmus: /dɪˈnɑːrməs/

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Habitat

Primarily associated with stored legume products and agricultural settings where bruchid occur. have been documented in cowpea storage systems, vetch fields, and other environments where pulse beetle develop on Fabaceae seeds.

Distribution

Almost . Documented occurrences include: semiarid regions of Rio Grande do Norte state (Brazil) on cowpea; widespread distribution in association with stored product bruchid pests globally.

Host Associations

Callosobruchus maculatus - Primary for D. basalis; pest of cowpea (Vigna unguiculata)
Callosobruchus chinensis - for D. basalis; pulse beetle pest
Bruchus brachialis - for D. acutus; vetch bruchid
Bruchidius atrolineatus - for D. basalis in laboratory studies
Zabrotes subfasciatus - Documented for D. basalis on genetically modified cowpea

Life Cycle

Larval-pupal ectoparasitoid development. Females deposit externally on larvae. Solitary development: typically one emerges per host, though occurs. Developmental plasticity observed in response to host quality and parasitoid .

Behavior

discrimination: females distinguish unparasitized hosts from those parasitized 8-72 hours previously by themselves or conspecifics, using host-quality markers including substances emitted during oviposition and larval-associated cues. Olfactory host location using chemical cues from hosts and host plants. Post- early learning involved in host recognition. occurs despite discrimination ability, with gains possible when second survival probability is favorable. Virgin females exhibit different host selection strategies than inseminated females, choosing smaller, easier hosts to maximize lifetime egg production. Facultative hyperparasitism documented as extreme survival .

Ecological Role

agent of bruchid beetles in stored legume products. Regulates of major agricultural pests including Callosobruchus that destroy cowpea and other pulse crops. Tritrophic interactions with legume plants and bruchid pests demonstrate cascading effects of plant macronutrient content on and sex ratios.

Human Relevance

Used in to prevent destruction of cowpea crops by Callosobruchus larvae. feeding supplementation (particularly honey) enhances progeny production and . Impact assessed in contexts of genetically modified crops and applications.

More Details

Sex allocation and host choice

Inseminated females of D. basalis manipulate offspring sex ratios and preferentially select larger, higher-quality (17-day-old vs. 12-13-day-old hosts), while virgin females produce only male offspring and select smaller hosts to maximize lifetime through energy conservation.

Nutritional ecology

Larval sugar content in C. maculatus positively correlates with D. basalis sex ratio and parameters, demonstrating bottom-up effects through the plant-pest- .

Superparasitism mechanisms

discrimination in D. basalis involves individual-specific markers; rates often exceed self-superparasitism rates. One deterrent substance is female-emitted during oviposition; another is released by 16-24 hour-old .